When do dogs start to age?

You can help! A short survey from the Family Dog Project explores how dog behavior changes with age, and when different breeds and breed types start showing signs of aging. All dog owners can participate, independently of their dogs’ age and breed!

There are still many unanswered questions regarding the natural ageing process in family dogs. While it is common knowledge that ageing leads to the decline of cognitive and physical abilities, the nature and dynamics of these declines is still very much under debate. So far, there is no agreement as to what age dogs start to show symptoms of ageing.

What makes this question complicated is that the average life span varies greatly among dog breeds, and so does the time they start ageing. Previous research has suggested that the larger the body size of the dog, the shorter its expected life span is, and the sooner it starts ageing. Depending on the size of the breed, there can be a more than two-fold difference in the expected life span between dogs. For example, on average a 10-20 kg dog lives to 13-14 years while a 70-80 kg dog lives only 7-8 years. This inverse relationship between life span and body size in dogs is surprising because the opposite can be observed among other mammalian species – typically larger species live longer than smaller.

Unfortunately, our understanding of what causes this phenomena is still incomplete. Moreover, most of the previous studies have investigated only purebred dogs, so we know very little about mixed breeds. Although the studies that involved mixes mostly agree that in general they live longer than purebreds. Among the possible causes of this difference, the most prominent is inbreeding, which (sadly) affects most of the breeds, and the over representation of a few popular sires in the breeding population. These factors may also be responsible for the unfortunate tendency that present day dogs do not live as long as they did 10 years ago. According to a survey in Great Britain, the average life span of most purebred dogs has decreased around 11% in the last ten years.

Another result of the same survey that is important to mention, is that approximately 40% of purebreds suffer from at least one health problem, and in the oldest dogs the figure rises to 85%. Among the many illnesses that affects old dogs, canine cognitive dysfunction, an age-related pathological cognitive decline in dogs, shares many similarities to the human Alzheimer’s disease.

Pathological cognitive decline in dogs is characterized by a variety of symptoms, among them, spatial disorientation, changes in the sleep-wake cycle, elimination problems, changes in social behaviour, memory problems and learning difficulties. Previous studies found that at the age of 11-12 years every second dog is affected by at least one of these problems, while at the age of 15-16, approximately two thirds are affected.

Again, it is currently unknown when these symptoms start to appear in different breeds, nor do we know which factors are linked to their appearance (e.g. being overweight, general lifestyle, sensory and musculoskeletal disorders), or how much they affect them.

The goal of our current study is to shed some light on these questions. We aim to collect information from owners of a large number of dogs from many different breeds (and mixed breed dogs) and size groups, to investigate how and how fast their behaviour changes with age and at what age do the symptoms of ageing and cognitive decline start to appear in different breed and size groups. We also aim to identify factors that may predispose dogs to cognitive decline, or prevent cognitive decline in dogs.

Age-related pathological cognitive decline (or dementia) has a serious negative impact on dogs’ quality of life and places substantial psychological and financial burdens on the owners, which make these questions all the more important to answer. Moreover, dogs share many ecological, ethological and physiological similarities with humans; therefore, they can be a natural model of human ageing as well. Hence, our study would not only help to fill some gaps in our knowledge about ageing and age-related cognitive decline in dogs, but could also provide a significant contribution to our understanding of human ageing and dementia.

You can help! A short survey from the Family Dog Project explores how dog behavior changes with age, and when different breeds and breed types start showing signs of aging. All dog owners can participate, independently of their dogs’ age and breed!

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